This is a lace webbed spider, or lace weaver (Amaurobius species), they are fairly common around the exterior & in our homes. They have fairly sizeable jaws and are able (when inadvertantly crushed against the skin, or handled) to deliver a bite. But they can't do us any real harm, localised redness, swelling & discomfort for a couple of days?

I see a lot of these in my home & have never personally had a problem with them, I do escort a few outside if I find them wandering about, but mostly they stick to the periphery of rooms, windows etc, where there is shelter & they can patrol their sticky, sheet like webs.

If you do find them out in the open on floors, ceilings, or walls they are quite easy to catch in a cone made of paper (be sure to fold over the point so they can't drop through) and put outside.

They sem to be a staple food of Pholcus phalangioides (daddy long legs/cellar spider) so if you don't like Amaurobius, then don't discourage the P. phalangioides and they may help to keep the population down?